Process and device for the manufacture of connecting seams between overlapping segments made of elastomeres or thermoplastic materials

ABSTRACT

In a process for connecting material segments made of an elastomere or of a thermoplastic material the sections to be joined (3,4) are placed between two pressure beams (1,2) in the area of the seam (5) to be created. The pressure beams are not mechanically connected to one another. The forces necessary to hold and to attach the material segments (3,4) are generated by the evacuation of suction chambers formed between the cavities (9) in the contact surfaces (6a,6b) of the pressure beams (1,2) and the segments to be joined (3,4).

BACKGROUND OF THE INVENTION

The invention regards a process and a device for the manufacture ofconnecting seams between overlapping material segments made ofelastomers or thermoplastic materials, especially roofing and sealingstrips.

In the case of, for example, flat roofs with so called roofing orsealing strips, the creation of joints, especially flat ones, betweenthe individual sealing strips or sheets creates enormous difficulties.

As a rule, sheets composed of individual strips are installed. Theprefabrication of sheets with a stationary device permits the easycreation of a permament watertight union by vulcanizing the individualoverlapping segments of the connecting seam. The connecting seamsbetween the individual strips manufactured on site are made by, forexample, gluing. The glued seam is generally covered by an adhesivestrip.

In the case of a frontal union of sheets made up of individual strips,so called T-joints are created. When the seams of both sheets converge,cross-joints are formed. These areas, due to the stepwise configurationof the connecting seam, create excessively weak spots and have to beadditionally reinforced by applying sealing paste or a similar material.

These glued joints have considerable disadvantages compared to thosemade by vulcanization. The sheets can virtually not be installed withoutstress. However, since glue requires a certain amount of time forcuring, the stress generated by the glue hardening process in the seamarea has a negative effect on the quality of the glued joint. Even afterthe glue has hardened, the resistance of the bonded area remainstemperature dependent. In the event of high temperatures (roofs canreach temperatures above 80° C.) the glued joint softens. In time, theeffects of fluctuating temperatures can damage the glued joint to suchan extent that it starts leaking. In this case extensive and costlyrepair work is necessary.

So far, the creation of flat vulcanized connecting seams made on sitefailed due to the fact that it was not possible to securely hold thestrips or sheets during vulcanization since the vulcanization device wasunable to hold the flat sheets, and consequently, the seam. Due to this,the pressure on the seam necessary for vulcanization can only be appliedby the weight of the vulcanization device itself. Consequently,correspondingly heavy devices would be necessary, but these would beextremely difficult to handle on construction sites, especially onroofs.

In order to avoid glued unions it has already been suggested to join thesheets with upright vulcanized seams. The edges of the installed sheetsare bent at a right angle, are pressed against one another in the seamarea, and are subsequently vulcanized. In this case, the vulcanizationdevice can hold the seam and the necessary pressure can be applied bymechanical or hydraulic displacement of both pressure bearing surfacesagainst one another.

SUMMARY OF THE INVENTION

However, in every case, strip seams require an additional covering, suchas, for example, a layer of gravel. T-joints and the connection ofsleeves, such as chimney enclosures and similar structures, can not becreated in a practical way.

The task of the present invention consists in describing a process and adevice to join overlapping segments of elastomers or thermoplasticmaterials, which is suited for the simple and economical creation ofpermanent and tight connecting seams, especially flat connecting seams,on construction sites or on roofs.

The task is solved according to the invention by placing the materialsegments to be joined between two pressure beams that are not connectedto one another by mechanical means. The contact surfaces of the pressurebeams have cavities outside of the seam area. The forces necessary tohold and join the segments are generated by the evacuation of suctionchambers formed between the cavities on the contact surfaces and thematerial segments to be joined placed above them.

A device to implement the process is characterized by the cavitiesconfigured on both sides of the seam area on the contact surfaces of thepressure beams. The cavities can also be connected to a suction pump.

With the process and device according to the invention tight andpermanent connecting seams can be created on construction sites and onroofs in a simple manner, especially flat connecting seams betweenoverlapping segments of materials made of elastomers or thermoplasticsubstances. The joint is made by, for example, vulcanization.

A pressure beam is placed underneath the segments to be joined so thatthe overlap area is on the seam area of the pressure beam. Both stripsare held by the lower pressure beam by evacuating the suction chamberscreated by the the cavities located on the sides of the seam area,within the contact surfaces of the pressure beam, and the sheets placedon top. Following this, the second pressure beam, which normallycontains the heating element, is placed on top of the lower beam and ispressed against the material by the atmospheric pressure present due tothe evacuation of the suction chamber created by the cavities betweenthe contact surfaces and the the sheets. The pressure generated in thisway is sufficient to vulcanize the connecting seam.

In an adequate manner, outside of the seam area, the contact surfaces ofthe pressure beams have been configured as ribs or burls. The evacuationof the suction chambers created by the cavities and the sheets placedabove them can be implemented by holes in the contact surfaces and bycollector channels configured underneath the contact surfaces, or theevacuation can be implemented by frontal collector channels.

The general cross-section of the rib depressions forming the suctionchambers can be configured in such a way by the selection of thepressure beam width, so that, one one hand, sufficiently large pressuresare generated by the atmospheric pressure when the suction chambers areevacuated. On the other hand, the peaks of the ribs or the surfaces ofthe burls will have been configured in such a way as to create asufficiently large contact surface, so that a flat placement of thesegments to be joined is assured within the holding area.

In the following, based on the single FIGURE which is a schematicrepresentation of an implementation example, the invention will beexplained in more detail.

The device according to the invention consists of two pressure beams,the upper beam 1 and the lower beam 2, which are not connected to oneanother by mechanical means. During vulcanization the segments 3, 4overlapping one another in the area of the seam 5 to be created, areheld between the contact surfaces 6a, 6b of the pressure beam 1, 2, arepressed, and finally attached to one another. The heating of the seam 5is accomplished by a bar shaped electric heating element 8, placedinside a central web of the upper beam 1. The heating element cancontain a built-in heat sensing element.

The contact surfaces 6a, 6b of the pressure beams 1,2 have cavities 9outside of the seam area 5. In the illustrated example, ribbed plates 10have been inserted into the contact surfaces 6a, 6b, the lengthwisegrooves of which form the cavities 9, while the rib peaks form asufficiently large contact surface for the segments 3,4 to be joined.

The cavities 9 are connected to channels 12 by holes 11. The channelshave been arranged underneath the ribbed plates 10. A suction pump canbe connected to these channels via connectors 13 located on the frontalarea of the pressure beam, or on the top of the beam, such as seen onbeam 1.

The suction chambers are formed by the cavities 9 and the segments 3, 4to be joined. On one hand, the evacuated suction chambers firmly holdthe segments 3,4 to be joined to the lower beam 2, and, on the otherhand, the upper beam 1 is pressed against the lower beam 2 with thematerial segments placed on it. The pressure necessary for vulcanizationcan be assured by establishing a sufficiently large width of thepressure beams 1, 2, and with it, of the total area of the cavitiesneeded for the creation of the suction chambers.

Additional gaskets 14 can be used to seal off the created suctionchambers. A certain amount of leakage is by all means allowable sincethe suction pump can remain in operation during the vulcanizationprocess.

To join both material segments 3,4, first the lower beam 2, which hasbeen provided with casters for easier handling, is placed underneath theopen seam 5. The material segments 3,4 placed on upon it are held inplace by evacuating the suction chambers. Following this, the upper beam1 is placed upon the lower beam and then both pressure beams are pressedagainst one another by evacuating the suction chambers on both beams 1,2until the vulcanization process has been completed. The length of thepressure beams 1,2 is only limited by the requirements of simple andeasy handling. Longer seams 5 can be made in several partial segmentswithout negative effects.

The heating element 8 has been designed to be pressure resistant and itprotrudes somewhat from the contact surfaces 6a, 6b of the pressurebeams 1, 2. This guarantees that the seam 5 to be created byvulcanization receives a sufficient amount of pressure. The protrudingsection of the heating element 8 is easily absorbed by the elasticity ofthe working material segments 3, 4 to be joined, as well as by thegaskets 14 that might be used. In addition, a silicone support 16 or asupport made of a different material can be placed on the seam area ofthe lower beam 2. This support can also have an incorporated heatingelement. Such a support could be advantageous for the creation ofT-joints.

To create closed seams, such as for the connection of sleeves or torepair damages in already installed sheets, the lower beam 2 can bereplaced by a simple plate made of i.e. silicone. This plate has beenadapted to the shape of the sleeve or of the seam and remains underneaththe installed sheet, since in this case, all that is needed is theavailability of a smooth lower surface. In this case, under certaincircumstances, such as when the seam cannot be composed of individualstraight partial segments, a pressure beam which has been adapted in itsshape to the shape of the seam must be used. However, the number ofnecessary specially shaped upper beams can be kept small by a certainstandardization of the shape and size of the individual sleeveconnections.

We claim:
 1. Process for the manufacture of connecting seams betweenoverlapping segments made of elastomers or thermoplastic materials,especially roofing strips and sealing strips, in which the segments tobe joined are pressed against one another and heated in the area of theseam to be created, comprising placing the segments to be joined betweentwo juxtaposed pressure beams that are not connected to one another bymechanical means, contact surfaces of the pressure beams having cavitiesoutside of the seam area, applying pressure necessary to join thesegments by evacuating suction chambers created by the cavities in thecontact surfaces and the segment surfaces to be joined, applying heat tothe seam area.
 2. The process of claim 1 further comprising,heatingalong the entire length of the seam area with heating means disposed inat least one pressure beam.
 3. The process of claim 2 wherein the seamarea is disposed centrally of the contact surface of the pressure beamcontaining the heating means, and the heating means comprises a heatingelement being adapted to the width of the seam to be created.
 4. Anapparatus for the manufacture of connecting seams between overlappingsegments made of elastomers or thermoplastic materials, especiallyroofing strips and sealing strips, comprising,first and second matingpressure beams having no mechanical connection to each other, eachpressure beam having contact surfaces and cavities formed in the contactsurfaces, evacuating means, in fluid communication with the cavities,for creating a vacuum in the cavities, heating means, disposed within atleast one of the pressure beams and overlying the seam area, for heatingthe seam area, and wherein material segments to be joined at the seamarea are held between the first and second pressure beams by the vacuumcreated in the cavities.
 5. The apparatus of claim 4 wherein the firstand second mating pressure beams comprises upper and lower pressurebeams.
 6. The apparatus of claim 5 wherein the heating means comprises aheating element disposed within the upper pressure beam.
 7. Theapparatus of claim 4 further comprising,gaskets disposed peripherallyaround the contact surfaces of the first and second pressure beams. 8.The apparatus of claim 6 wherein the cavities are connected to channelsdisposed beneath the contact surfaces by means of holes.
 9. Theapparatus of claim 6 wherein the heating element protrudes beyond thecontact surfaces for applying pressure to the seam area.
 10. Anapparatus for creating closed seams, such as for the connector ofsleeves or the repair damages in previously installed sheets,comprising,an upper pressure beam having contact surfaces and cavitiesformed in the contact surfaces, a lower plate disposed beneath thepressure beam, wherein the plate is adapted to the shape of the sleeveor of the seam and remains underneath the installed sheet, evacuatingmeans, in fluid communication with the cavities, for creating a vacuumin the cavities, heating means, disposed within the pressure beam, andoverlying the seam area, for heating the seam area, and wherein materialsegments are held between the pressure beam and the plate by vacuumcreated in the cavities.